In the weeks after Sachiko Kuno and Ryuji Ueno bought two of the largest historic properties in Georgetown — for a combined $33 million — questions and rumors swirled.

Who were they? How had they become so fabulously wealthy? And what did they plan to do with these properties?

It was said the pair had bought a house in Georgetown just for their cats. (Not true, Kuno says.) It was said they bought another in Potomac just for parties. (A little more true, as it turns out.)

Little about the Japanese couple was known beyond the fact that they had founded a company in Bethesda that makes a drug for chronic constipation and that it went public in 2007. They were rarely glimpsed at parties. Few in the community dominated by Washington’s old guard had heard of them. They declined interviews through an attorney, who described the couple as “very low-key” and “media-shy.”

The Maryland biotech tycoons stayed anonymous after the $22 million contract was signed on Evermay, the Federal-style mansion with lush gardens that sits high on a hill on 28th Street NW and boasts a stellar view of the Washington Monument. And they offered little more information shortly after when they bought nearby Halcyon House for about $11 million.

Biotech tycoons Sachiko Kuno (left) and Ryuji Ueno at their newly purchased Evermay Estate in Washington, DC on April 3, 2012. The couple purchased the estate, along with Halycon House in Georgetown for a cool $22 million. (Linda Davidson/THE WASHINGTON POST)

“It did seem like they came out of nowhere,” says Leslie L. Buhler, executive director of the nonprofit group that runs Tudor Place, one of the neighborhood’s other historic homes. “Nobody suspected, imagined or knew of them, and they were people that had very little experience with George­town, so it was a surprise.”

They are sitting side-by-side at a long, polished table in Evermay’s dining room for their first major interview together, conducted under the watchful eye of a publicist and an employee on hand to translate if needed. A marble fountain burbles outside, where the formal gardens are in full bloom. The freshly painted walls are hung with gilt-framed mirrors and antique Japanese screens.

Dressed in business attire, the couple — Ueno, 58, the brainy scientist, and Kuno, 57, his business-savvy wife — appear as formal and proper as their surroundings, even as they exhibit a gentle playfulness with each other. (At one point, Ueno joked that for a long time after they met, they were more interested in talking about “exciting chemical compounds” than romance.) They revert to Japanese only rarely during the conversation.

They are gracious but also reserved, reluctant to speak in detail about their personal lives. (It’s a good hour into the interview before they reveal that, although they’ve been friends and business partners since the 1980s, they did not get married until 2002, after each went through a divorce.)

“For the 15 years we’ve been here, we’ve been focusing on business issues and not going to parties or having big exposure,” Kuno said. “We didn’t realize or recognize that we had to be prepared to expose somewhat our names and what we are doing here. It’s a very big responsibility to keep these two wonderful historic houses, and we want to do our best to preserve them.”

The couple took one look at Evermay’s blooming flower beds, large ballroom and amazing view and fell in love. They practically bought the home on impulse.

“It was the first impression,” Ueno says. “We talked about it for five minutes.”

They say they want to live in the house — someday! — but for now they will be using it as a small gathering space and guest house for the S&R Foundation, which they created in 2000 to bolster the careers of promising young classical musicians and scientists.

“It’s kind of like a national treasure,” Kuno says. “We don’t think we can just be occupying it personally; instead we’d like to use it for the foundation or sometimes open it up to the public.”

For the time being, the two remain in the Potomac Falls neighborhood in Montgomery County near the Chesapeake & Ohio Canal. There, just as in Georgetown, the neighbors have found them a tad mysterious.

Over the past eight years, they’ve spent $11 million on five homes in the neighborhood, real estate records show, and hired noted landscape architect Jay Graham to build a woodland path connecting the homes, with a stone bridge and a wood bridge and a tiny pond. The couple use the path often to walk their golden retriever, Mario.

One of the homes — dubbed “the Clubhouse” — is used primarily for entertaining, but the folks in the neighborhood of stately houses and tall oaks can’t figure out what’s happening with the others. (The couple have said they are “guest houses” for visiting scientists, artists or relatives from Japan.)

“The guy [Ueno] comes in spending millions of dollars, buying every house he gets his hands on. . . . Everything they’ve bought they’ve made it into a palace,” says Samuel Moerman, a retired lawyer who lives next door. “They seem to have endless amounts of money.”

The couple also have a house on P Street in Georgetown, a condo in New York and two properties on the Eastern Shore, where they belong to the local yacht club but are rarely seen.

The couple say that they don’t make it out there as much as they like because they are so often working. Ask them what they do for fun, and Kuno laughs and says, “Fun? What is fun?”

Start in Japan

When they arrived in the United States in 1996, the pair had already created a successful pharmaceutical company in Japan that makes eyedrops to treat glaucoma. They wanted to create a U.S. company that would build on a technology that Ueno had discovered and patented. (It involves a series of compounds called prostones that can restore and heal organs and cells in the body.)

Ueno is from a very wealthy family of inventors from the suburbs of Osaka; his grandfather owned an early prototype of an electric car, and his father, Ryuzo, founded a chemical company that did so well that he was able to help finance his son’s effort to develop the eyedrops — to the tune of $80­­ million.

The early decade in Japan, developing the first drug, was full of debt and uncertainty, Ueno says, which put a strain on his relationship with his father.

In fact, after his sons from his first marriage grew up as witnesses to the family tension, they both swore they would not be the fourth generation of Uenos to become entrepreneur-inventors.

“My father started to be very angry because the debt was growing too big, and he was not in too good of a temper when he talked to me,” Ueno says. “My sons decided they would go into business straight. . . . The older one said his ideal goal was to have a stable life.”

Both ultimately followed more traditional career paths: One is now 30 and an auto company employee in Ann Arbor, Mich., and the other is 27 and an accountant in Tokyo.

Ueno and Kuno — who was a researcher in Ueno’s experimental lab when they met in 1982 — founded Sucampo Pharmaceuticals in Bethesda in 1996 and began expanding on Ueno’s research. Ten years later, their work paid off when the Food and Drug Administration approved their new drug, Amitiza, to treat chronic constipation. It was later approved for the treatment of irritable bowel syndrome, too.

“They are born risk takers who are not afraid to try something new,” says Kei Tolliver, who has worked for the couple since 1998 and now oversees their private-asset holding company. “It was challenging, but I think they enjoyed it.”

The couple own the majority stake in the $300 million company. Amitiza brings Sucampo between $200 million and $250 million in revenue a year, according to Securities and Exchange Commission filings.

But not everything is rosy. Analysts say Sucampo struggled to live up to the promise of its initial public offering in 2007 and has gone through several high-level managers in several years. Some of these employees have said the couple can be difficult to work with. Further, Amitiza does not always help all patients. And it faces a potential challenger to its market share — a new drug that’s performed well in clinical trials and could be on the market by this fall.

Higher profile

In the months since the couple have emerged as the stewards of two of Georgetown’s most important properties, they have begun to raise their profile a bit. This spring they threw a dinner at Evermay before the Opera Ball, and they were the star guests at Tudor Place’s annual garden party. At the later event, board members made a point to show Ueno, an automobile enthusiast, Tudor Place’s vintage car. He told them he has a collection of about 60 cars, which has included Ferraris and a Morgan roadster.

They have taken great care to win over the neighbors of Evermay, inviting them to a reception to listen to concerns and fears that the couple would rent out the home for large-scale weddings and corporate events — as the previous owners had. (It was a “party factory,” one sniffed.)

“They’ve always been gracious, friendly and very dedicated to fitting in in a way that’s appropriate for the property and the neighborhood,” says Ellen Steury, a lawyer who lives nearby.

As the refurbishment of Evermay nears completion, the couple are turning their attention to Halcyon House, the Prospect Street home built in 1787 by the first Navy secretary, Benjamin Stoddert, which the couple bought in November. This house, too, has amazing views. “You can relax by the pool with a bottle of Chateauneuf-du-Pape and watch people stuck in Key Bridge traffic,” one of the original listing agents once said.

In preserving the two grand homes and their other philanthropic endeavors — such as helping underwrite the current exhibition of Kyoto silks at the Textile Museum — the couple say they want to continue to give back to a local community that embraced them when they moved here in 1996, just two entrepreneurs with a dream.

“From the beginning we were talking, if we made some success, we would like to share with people in the States or in the Washington area,” Ueno says. “After we left Japan, we think it’s better to share such gold.”

Researcher Magda Jean-Louis contributed to this report.

Annie GowenAnnie Gowen is a correspondent for The Washington Post's National desk. She was previously The Post’s India bureau chief and has reported for The Post throughout South Asia and the Middle East since 2013. Before going to India, she was a member of The Post's social issues team covering wealth and inequality. Follow